Happy birthday, Half-Life! To celebrate, we all get to buy Black Mesa.

Black Mesa, the fan-made Half-Life remake that was released last year, has always been a totally free mod, but today, the folks behind the project announced that they've got plans to start selling a paid version, too.

"Our decision to sell Black Mesa rests on two key points," writes project leader Carlos Montero. "One is we believe we can make the game even better by having full access to the Source engine. This lets us tackle and fix limitations instead of working around them. The second is because frankly, our team could really use the financial help."

To quote Montero:

The Plan:

Soon you'll see Black Mesa available on Steam for a relatively low price. But we aren't dropping all support for the free version. In fact shortly after the Steam release there will be a completely new free version of the game. We also plan to open source our maps and some game assets to the modding community!

Purchasing the Steam version of Black Mesa is more about supporting the team and our efforts than anything else. However, the Steam version will include features that the free version simply can not have. We will be paying careful attention to feedback, and you'll have a very real say in how the final game turns out.

No word when this premium version of Black Mesa will go on sale. This is one of those late birthday present deals. In the meantime, take a few minutes to think about the fact that holy crap Half-Life is 15.